Capacitive position sensing for camera focus management

ABSTRACT

An apparatus includes a lens assembly that includes at least one lens that defines an optical axis. The apparatus also includes a substrate, an image sensor disposed on the substrate, and an actuator coupled to the substrate and configured to adjust a position of the substrate relative to the lens assembly to move the image sensor along the optical axis. The apparatus additionally includes a capacitive position sensor that includes a first capacitive plate coupled to the substrate and a second capacitive plate coupled to the lens assembly. The capacitive position sensor may be configured to generate a capacitance measurement indicative of the position of the substrate relative to the lens assembly. The apparatus further includes circuitry configured to control the actuator based on (i) the capacitance measurement and (ii) a target position of the image sensor relative to the lens assembly.

BACKGROUND

An optical system may include one or more lenses and an image sensor.The image sensor may include a plurality of light-sensing pixels thatmeasure an intensity of light incident thereon and thereby collectivelycapture an image of an environment. A Bayer filter may be applied to theimage sensor to allow the image sensor to generate color images of theenvironment. Optical systems may be used in a plurality of applicationssuch as photography, robotics, and autonomous and/or semi-autonomousvehicles that are configured to operate in one or more driving modes,such as fully autonomous mode or partially autonomous mode (e.g., driverassistance, adaptive cruise control, etc.).

SUMMARY

An optical system may include an actuator configured to reposition animage sensor relative to an optical axis of one or more lenses. Theimage sensor may be repositioned, for example, to maintain the imagesensor within a depth of focus of the one or more lenses. The actuatormay allow the optical system to compensate for changes in positioning ofthe image sensor relative to the depth of focus caused by temperaturevariations, mechanical perturbations, and/or component aging, amongother factors. A position of the image sensor may be determined using acapacitive position sensor, which may include at least (i) a firstcapacitive plate coupled to a substrate on which the image sensor isdisposed and (ii) a second capacitive plate coupled to a lens assemblythat includes the one or more lenses. Variations in relative positionbetween the one or more lenses and the image sensor may generate acorresponding change in capacitance between the first and secondcapacitive plates, which may be measured and used to determine theposition of the image sensor. The optical system may also includecircuitry configured to measure the capacitance between at least thefirst and second capacitive plates, determine the position of the imagesensor based on the measured capacitance, and generate a control signalconfigured to cause the actuator to reposition the image sensor to atarget position (e.g., within the depth of focus).

In a first example embodiment, an apparatus may include a lens assemblythat includes at least one lens that defines an optical axis. Theapparatus may also include a substrate, an image sensor disposed on thesubstrate, and an actuator coupled to the substrate and configured toadjust a position of the substrate relative to the lens assembly to movethe image sensor along the optical axis. The apparatus may additionallyinclude a capacitive position sensor that includes a first capacitiveplate coupled to the substrate and a second capacitive plate coupled tothe lens assembly. The capacitive position sensor may be configured togenerate a capacitance measurement indicative of the position of thesubstrate relative to the lens assembly. The apparatus may furtherinclude circuitry configured to control the actuator based on (i) thecapacitance measurement and (ii) a target position of the image sensorrelative to the lens assembly.

In a second example embodiment, a method may include receiving, from acapacitive position sensor, a capacitance measurement indicative of aposition of a substrate relative to a lens assembly. The lens assemblymay include at least one lens that defines an optical axis. An imagesensor may be disposed on the substrate. The capacitive position sensormay include a first capacitive plate coupled to the substrate and asecond capacitive plate coupled to the lens assembly. The method mayalso include determining, based on the capacitance measurement and atarget position of the image sensor relative to the lens assembly, acontrol signal for an actuator that is coupled to the substrate andconfigured to adjust the position of the substrate relative to the lensassembly to move the image sensor along the optical axis. The method mayfurther include providing the control signal to the actuator to move thesubstrate to the target position.

In a third example embodiment, a system may include a processor and anon-transitory computer-readable medium having stored thereoninstructions that, when executed by the processor, cause the processorto perform operations in accordance with the second example embodiment.

In a fourth example embodiment, a non-transitory computer-readablemedium may have stored thereon instructions that, when executed by acomputing device, cause the computing device to perform operations inaccordance with the second example embodiment.

In a fifth example embodiment, a system may include a lens assembly thatincludes at least one lens that defines an optical axis. The system mayalso include a substrate, an image sensing means disposed on thesubstrate, and an actuating means coupled to the substrate andconfigured to adjust a position of the substrate relative to the lensassembly to move the image sensing means along the optical axis. Thesystem may additionally include a capacitive position sensing means thatincludes a first capacitive plate means coupled to the substrate and asecond capacitive plate means coupled to the lens assembly. Thecapacitive position sensing means may be configured to generate acapacitance measurement indicative of the position of the substraterelative to the lens assembly. The system may further include means forcontrolling the actuating means based on (i) the capacitance measurementand (ii) a target position of the image sensing means relative to thelens assembly.

These, as well as other embodiments, aspects, advantages, andalternatives, will become apparent to those of ordinary skill in the artby reading the following detailed description, with reference whereappropriate to the accompanying drawings. Further, this summary andother descriptions and figures provided herein are intended toillustrate embodiments by way of example only and, as such, thatnumerous variations are possible. For instance, structural elements andprocess steps can be rearranged, combined, distributed, eliminated, orotherwise changed, while remaining within the scope of the embodimentsas claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a sensor system, in accordance with exampleembodiments.

FIG. 2 illustrates an optical system, in accordance with exampleembodiments.

FIGS. 3A, 3B, 3C, 3D, and 3E illustrate a vehicle, in accordance withexample embodiments.

FIG. 4A illustrates an optical system with a capacitive position sensor,in accordance with example embodiments.

FIG. 4B illustrates an optical system with a differential capacitiveposition sensor, in accordance with example embodiments.

FIG. 4C illustrates an optical system with a tongue-and-groovecapacitive position sensor, in accordance with example embodiments.

FIGS. 5A and 5B illustrate an electrode arrangement for a capacitiveplate, in accordance with example embodiments.

FIG. 6 illustrates a top view of aspects of an optical system, inaccordance with example embodiments.

FIG. 7 illustrates a flow chart, in accordance with example embodiments.

DETAILED DESCRIPTION

Example methods, devices, and systems are described herein. It should beunderstood that the words “example” and “exemplary” are used herein tomean “serving as an example, instance, or illustration.” Any embodimentor feature described herein as being an “example,” “exemplary,” and/or“illustrative” is not necessarily to be construed as preferred oradvantageous over other embodiments or features unless stated as such.Thus, other embodiments can be utilized and other changes can be madewithout departing from the scope of the subject matter presented herein.

Accordingly, the example embodiments described herein are not meant tobe limiting. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations.

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall embodiments, with the understanding that not allillustrated features are necessary for each embodiment.

Additionally, any enumeration of elements, blocks, or steps in thisspecification or the claims is for purposes of clarity. Thus, suchenumeration should not be interpreted to require or imply that theseelements, blocks, or steps adhere to a particular arrangement or arecarried out in a particular order. Unless otherwise noted, figures arenot drawn to scale.

I. OVERVIEW

A camera device may include an image sensor and a lens assembly. Thelens assembly may include one or more lenses that are configured tofocus light on the image sensor and a lens holder configured to positionthe one or more lenses relative to other components of the cameradevice. The image sensor may be disposed on a substrate, such as aprinted circuit board (PCB), which may be positioned relative to thelens assembly. When the relative positioning of the image sensor and thelens is fixed, it may be difficult to maintain the image sensor within adepth of focus of the lens assembly when camera components expand andcontract due to changes in operating conditions (e.g., temperature,humidity, mechanical perturbations, component aging, etc.). This may beespecially problematic in automotive applications where, in addition tothermal gradients inside the camera, ambient temperatures experienced bythe camera may fluctuate between, for example, −30 degrees Celsius and85 degrees Celsius.

For example, different portions of the camera may expand and contract todifferent extents due to temperature changes, causing the image sensorto drift in and out of the depth of focus of the lens assembly,resulting in generation of out-of-focus images. The problem may beespecially apparent where the image sensor includes a small pixel size(resulting in a smaller image sensor) and/or the lens has a lowf-number, resulting in a small or shallow depth of focus (e.g.,approximately 10-15 microns). A low depth of focus may limit the maximumextent of warpage of the image sensor that can occur before thegenerated images are out of focus.

An actuator may be connected between the substrate and the lens holderto allow for adjustments in the position of the image sensor at leastalong the optical axis of the lens. For example, the actuator mayinclude a stack of one or more linear piezoelectric actuators, apiezoelectric tube actuator, and/or a bending actuator positioned alonga plane defined by the substrate. The actuator may shorten, contract,and/or bend in a first direction to move the image sensor in a firstdirection relative to the lens (e.g., toward the lens), and maylengthen, expand, and/or bend in a second direction to move the imagesensor in a second direction relative to the lens (e.g., away from thelens). Additionally or alternatively, the actuator may include anelectric motor. Moving the image sensor, rather than the lens, mayfacilitate sealing of the camera components within a compact housing.Further, since the combined weight of the image sensor and the substratemay be smaller than that of the lens assembly, moving the image sensorand substrate may involve less force than moving the lens.

The camera may also include a position sensor connected to the lensassembly and the substrate and configured to provide position feedbackthat allows the image sensor to be accurately positioned relative to theone or more lenses. The position sensor may be a capacitive positionsensor that includes one or more capacitors. Specifically, a capacitorof the capacitive position sensor may include a first capacitive platecoupled to and/or defined on the substrate and a second capacitive platecoupled to and/or defined by part of the lens assembly. Thus, thecapacitance of the capacitor may vary based on a relative positionbetween the substrate and the lens assembly. Accordingly, the capacitiveposition sensor may be configured to generate a capacitance measurementthat indicates the position of the substrate relative to the lensassembly. For example, the capacitance measurement may vary as afunction of (e.g., may be inversely proportional to) the position of thesubstrate.

The capacitive position sensor may be easier to implement as part of thecamera than other types of position sensors. In one example, acapacitive plate may be coupled to and/or defined on the substrate usingthe same or similar processes as other features of the substrate, andmay thus be formed by modifying existing manufacturing operations ratherthan adding additional operations. In another example, a capacitiveplate may be defined to be integral with the lens assembly, and may thusbe formed by shaping parts of the lens assembly rather than attachingadditional components thereto. Additionally, the capacitive positionsensor may include arrangements that compensate for variations intemperature, humidity, mechanical perturbations, and/or component aging,thereby allowing the capacitive position sensor to measure the positionof the substrate more accurately than other types of position sensors.For example, as discussed below, differential arrangements of thecapacitive plates and/or usage of shielding electrodes may improve theposition measurement accuracy relative to other types of positionsensors and/or arrangements thereof.

In one example, the first capacitive plate may be driven with a voltage(e.g., a time-varying signal), while the second capacitive plate may beheld at a fixed voltage (e.g., ground). In some implementations, areference capacitor that has a known/predetermined capacitance may beused in determining the capacitance measurement. Placement of the first(driven) capacitive plate on the substrate (e.g., a PCB), rather than onthe lens assembly, may facilitate the establishment of electricalconnections to the capacitive position sensor.

Control circuitry may be configured to determine and/or receive thecapacitance measurement, determine a distance between the lens assemblyand the image sensor, and control the actuator to adjust the distance toa target distance (e.g., a distance that places the image sensor withinthe depth of focus of the one or more lenses). The capacitive positionsensor may also allow the effects of any hysteresis or nonlinearities inthe actuator to be accounted and/or compensated for when repositioningthe substrate.

In some implementations, the capacitive position sensor may include twocapacitors. A first capacitor may be disposed on a first side (e.g., topside) of the substrate and a second capacitor may be disposed on asecond side (e.g., bottom side) of the substrate. For example, the firstcapacitor may be formed from a first capacitive plate defined on thefirst side of the substrate and a second capacitive plate defined by afirst portion of the lens assembly (e.g., the lens holder). The secondcapacitor may be formed from a third capacitive plate defined on thesecond side of the substrate and a fourth capacitive plate defined by asecond portion of the lens assembly (e.g., an actuator frame). The firstportion of the lens assembly may face the first side of the substrateand may be parallel therewith, thereby forming a first parallel platecapacitor. Similarly, the second portion of the lens assembly may facethe second side of the substrate and may be parallel therewith, therebyforming a second parallel plate capacitor. The first portion of the lensassembly and the second portion of the lens assembly may each be formedfrom a conductive material.

The control circuitry may be configured to receive a respectivecapacitance measurement from each of the first capacitor and the secondcapacitor, and determine a difference signal based thereon. For example,the control circuitry may be configured to subtract a second capacitancemeasurement of the second capacitor from a first capacitance measurementof the first capacitor. The control circuitry may be configured todetermine the position of the substrate relative to the lens assemblybased on the difference signal (e.g., using a mapping of differencesignal values to physical substrate positions). Such differentialsensing of substrate position may (i) reduce and/or minimize asensitivity of the capacitive position sensor to sources of common modenoise, including temperature, humidity, and component aging, (ii) reduceparasitic loading on electronic components associated with thecapacitive position sensor, (iii) improve linearity and reduce gainerror of the capacitive position sensor, and (iv) increase a sensitivityand/or resolution of the capacitive position sensor.

In some implementations, the first and third capacitive plates may eachinclude a respective sensor electrode and respective one or more shieldelectrodes positioned adjacent to the respective sensor electrode. Thesensor electrode and the one or more shield electrodes may be drivenusing a common signal (e.g., a time-varying voltage), and may therebydefine a sensing zone of the sensor electrode. When actively driven, theshield electrodes may linearize an electric field associated with thesensing electrode, and may reduce or eliminate a sensitivity of thesensor electrode to stray capacitance.

Additionally, in some implementations, a width and length of thecapacitive plates formed by the lens assembly may be larger than a widthand length, respectively, of corresponding capacitive plates formed onthe substrate. Thus, the capacitive position sensor may be configured tomeasure substrate movements along the optical axis, but may berelatively insensitive to substrate movement perpendicular to theoptical axis. In some implementations, capacitive plates formed on thesubstrate may be shaped to define a groove, while capacitive platesformed by the lens assembly may be shaped to define a tongue that isconfigured to fit in and move relative to the groove.

The control circuitry may be configured to determine a target positionat which to place the image sensor relative to the lens assembly basedon a temperature measured at one or more locations within the cameradevice, and/or an extent of focus measured based on one or more imagescaptured by the image sensor. For example, the control circuitry mayimplement an algorithm or model (e.g., a contrast detection algorithm, aphase detection algorithm, and/or a neural network model) configured todetermine a focus score indicative of an extent to which at least oneobject (e.g., an object in an environment, a calibration target) in theone or more images is in-focus. The control circuitry may also beconfigured to determine the target position based on the focus score.For example, the target focus score may be selected to reduce and/orminimize an extent of defocus associated with the at least one object.

As temperature changes are observed by one or more temperature sensors,the control circuitry may be configured to adjust the target position tomaintain the reduction and/or minimization of the extent of defocusassociated with the at least one object (e.g., based on a predetermineddrift of the position of the focal plane per degree Celsius). In oneexample, the focal plane may be determined to drift along the opticalaxis by up to 25 micrometers across a temperature range of 100 degreesCelsius (e.g., −15 degrees Celsius to 85 degrees Celsius), resulting inan average drift of 0.25 micrometers per degree Celsius. Accordingly,the target position may be adjusted by 0.25 μm/° C. relative to aposition that, for a given set of environmental conditions, reducesand/or minimizes the extent of defocus associated with the at least oneobject. Additionally or alternatively, one or more humidity sensors maybe used to measure the humidity (e.g., relative and/or absolute) at oneor more locations within the camera device, and the control circuitrymay be configured to adjust the target position accordingly (e.g., basedon a predetermined amount of drift per unit change in humidity). Therate of drift of the focal plane may be calibrated on a per-camera-modelbasis and/or a per-camera basis to account for model-specific and/ordevice-specific variations.

II. EXAMPLE OPTICAL SYSTEMS

FIG. 1 illustrates a sensor system 100. Sensor system 100 may representan optical system that includes lens assembly 110, substrate 130, imagesensor 140, thermal sensor 170, capacitive position sensor 180,controller 186, and actuator(s) 194. In some embodiments, sensor system100 may include and/or represent a camera system and/or a lightdetection and ranging (LIDAR) system. That is, sensor system 100 couldinclude and/or represent systems for capturing video and/or stillimages, and/or LIDAR point cloud data. In some implementations, sensorsystem 100 may include and/or be used in combination with other types ofsensors, such as, for example, radar devices, inertial sensors, and/oraudio sensors, among other possibilities.

Lens assembly 110 may include one or more lens(es) 112. Lens(es) 112 maydefine an optical axis 114, a focal distance 116, and a focal plane 118,among other optical characteristics. Lens(es) 112 could include, forexample, a spherical lens, an aspherical lens, a cylindrical lens, aFresnel lens, a gradient index lens, and/or a diffractive optical lens,among other possibilities. Lens(es) 112 could be formed from plastic,glass, or another optical material. Lens assembly 110 may also includelens holder 120, which may be coupled to lens(es) 112 to positionlens(es) 112 with respect to substrate 130 and/or image sensor 140,among other components. Lens assembly 110 may further include actuatorframe 160, which may be coupled to lens holder 120 to positionactuator(s) 194 with respect to lens(es) 112 and/or substrate 130, amongother components. Lens holder 120 and/or actuator frame 160 may, in somecases, be viewed as components that are independent of lens assembly 110(rather than a subset thereof).

Substrate 130 may include a first (e.g., top) surface/side and a second(e.g., bottom) surface/side. In some embodiments, substrate 130 couldinclude a printed circuit board (PCB), a semiconductor substrate, oranother flexible or rigid body. Image sensor 140 may be attached to thefirst surface/side of substrate 130. The material of substrate 130 maybe selected, for example, to (i) match a coefficient of thermalexpansion (CTE) of image sensor 140 and/or (ii) provide high thermalconductivity to allow for efficient cooling of image sensor 140, amongother considerations. For example, substrate 130 may include a ceramicPCB made out of aluminum oxide, aluminum nitride, beryllium oxide, oranother ceramic material. In some implementations, the ceramic PCB maybe a co-fired ceramic, such as a high temperature co-fired ceramic(HTCC) or a low temperature co-fired ceramic (LTCC). Alternatively oradditionally, substrate 130 may include a low-CTE FR-4 material (i.e.,fiberglass layers bonded with epoxy resin). In one example, the ceramicPCB may be bonded to image sensor 140 by way of a ball grid array.

In some implementations, one or more additional PCBs may be coupled tolens holder 120. The additional PCBs may include electrical connector(s)and/or electrical component(s), and may be electrically connected tosubstrate 130 by way of flexible PCB connector(s). The additional PCB(s)may include, for example, a laminate-based PCB configured to accommodaterepeated plugging into and unplugging from the electrical connector(s).The laminate-based PCB may be formed from laminae bonded together with apolymer resin. For example, the laminate-based PCB may be an FR-4 board,a CEM-3 board, or another non-ceramic material having similar physicalproperties.

The flexible PCB connector(s) may provide a variable bend radius toaccommodate repositioning of lens assembly 110, on which the additionalPCB is mounted, relative to substrate 130. The electrical connector(s)provided on the additional PCB(s) may be exposed outside of a housing ofsensor system 100 and configured to provide at least a portion ofsignals generated by image sensor 140. The electrical component(s)provided on the additional PCB(s) may be configured to process signalsgenerated by image sensor 140, capacitive position sensor 180, and/orother components of sensor system 100 (e.g., before such signals areexposed outside of the housing by way of the electrical connector(s)).

Actuator(s) 194 may be configured to reposition image sensor 140 to atarget position relative to lens assembly 110. Actuator(s) 194 may beconfigured to maintain image sensor 140 at focal plane 118 and/or withina depth of focus of lens assembly 110 over a predetermined temperaturerange (e.g., −30 to 85° C.). That is, the target position may be atfocal plane 118 and/or within the depth of focus of lens assembly 110(e.g., within a threshold distance above and below focal plane 118).

Actuator(s) 194 may include piezoelectric structure(s) 196 coupledbetween actuator frame 160 and substrate 130. In some embodiments, atleast a portion of piezoelectric structure(s) 196 could be arrangedcoaxially about the optical axis 114. Piezoelectric structure(s) 196 maybe formed from a variety of piezoelectric materials, including, but notlimited to, lead zirconate titanate (e.g., PZT), lithium niobate, bariumtitanate, potassium niobate, sodium tungstate, sodium potassium niobate,and/or bismuth ferrite, among other possibilities.

In some embodiments, piezoelectric structure(s) 196 could include apiezoelectric tube. For example, the piezoelectric tube could be apiezoelectric tube actuator, such as Thorlabs PT49LM or PI PT120-PT140Series piezo tubes. In some embodiments, the piezoelectric tube could beconfigured to provide a desired axial expansion/contraction value and/ora desired diameter expansion/contraction value (e.g., based on a knownand/or expected thermally-induced expansion or contraction of variouscomponents of sensor system 100). The piezoelectric tube may becontrollable so as to adjust at least one of (i) a distance betweenlens(es) 112 and image sensor 140 or (ii) a tip or tilt of image sensor140 with respect to focal plane 118, among other aspects of thegeometric arrangement of elements in sensor system 100.

In other embodiments, piezoelectric structure(s) 196 could additionallyor alternatively include a piezoelectric linear actuator. For example,the piezoelectric linear actuator may include a plurality ofpiezoelectric linear actuators stacked on top of one another. In someembodiments, the piezoelectric linear actuator could be configured toprovide a desired axial expansion/contraction value (e.g., based on aknown or expected thermally-induced expansion or contraction of variouscomponents of sensor system 100).

In some implementations, piezoelectric structure(s) 196 could form twoor more stacks or posts arranged at respective positions along substrate130. For example, piezoelectric linear actuators may form four stacks,with a first stack positioned above image sensor 140, a second stackpositioned below image sensor 140, a third stack positioned to the rightof image sensor 140, and a fourth stack positioned to the left of imagesensor 140 (when viewed from a top view). In such a scenario, each ofthe stacks could be configured to be separately controllable so as toadjust at least one of (i) a distance between lens(es) 112 and imagesensor 140 or (ii) a tip or tilt of image sensor 140 with respect tofocal plane 118, among other aspects of the geometric arrangement ofelements in sensor system 100.

In various embodiments, actuator(s) 194 may additionally oralternatively include other types of actuators, such as, for example,stepper motor 198. For example, actuator(s) 194 could includepiezoelectric structure(s) 196 and stepper motor 198, which could beconfigured to provide micro and macro movements, respectively, in theaxial direction. In other words, piezoelectric structure(s) 196 could beutilized to provide fine axial position adjustments (e.g., less than±100 microns) and stepper motor 198 could be configured to providecoarse axial position adjustments (e.g., greater than ±100 microns).Additionally or alternatively, actuator(s) 194 may include a voice coilactuator.

In some embodiments, sensor system 100 could additionally includethermal sensor 170. Thermal sensor 170 may be configured to provideinformation indicative of a current temperature of at least a portion ofsensor system 100. In such a scenario, at least one property ofactuator(s) 194 could be configured to be adjusted based on the currenttemperature. In some embodiments, thermal sensor 170 could include athermocouple, a thermometer, a thermistor, a semiconductor-based device,and/or another type of temperature-sensing device. In someimplementations, thermal sensor 170 may be integrated with image sensor140. Thermal sensor 170 may include a plurality of thermal sensorsdistributed throughout the housing of sensor system 100, and may thus becapable of monitoring temperature gradients within the housing.

Additionally, sensor system 100 may include capacitive position sensor180. Capacitive position sensor 180 may be configured to provideinformation indicative of a position of image sensor 140 and/orsubstrate 130 with respect to lens assembly 110 (e.g., with respect tolens holder 120 and/or actuator frame 160). In such scenarios, at leastone property of actuator(s) 194 may be configured to be adjusted basedon the position of image sensor 140 and/or substrate 130 with respect tolens assembly 110.

In some embodiments, capacitive position sensor 180 may include firstcapacitive plate 182 and second capacitive plate 184. For example, firstcapacitive plate 182 may be coupled to, mounted on, formed on, and/ordefined on substrate 130, and second capacitive plate 184 may be coupledto, mounted on, formed on, and/or defined on lens assembly 110 (e.g., onlens holder 120 and/or actuator frame 160). Additionally oralternatively, sensor system 100 may include a magnetic position sensor,an ultrasonic position sensor, an inductive position sensor, an opticalposition sensor, and/or a laser-doppler vibrometer. Other types ofposition sensors are possible and contemplated.

In some embodiments, sensor system 100 could also include controller186. Controller 186 may include one or more processor(s) 188 and memory190. Additionally or alternatively, controller 186 may include afield-programmable gate array (FPGA) and/or an application-specificintegrated circuit (ASIC). As an example, processor(s) 188 may include ageneral-purpose processor or a special-purpose processor (e.g., digitalsignal processors, etc.). Processor(s) 188 may be configured to executecomputer-readable program instructions that are stored in memory 190. Insome embodiments, processor(s) 188 may execute the program instructionsto provide at least some of the functionality and operations describedherein.

Memory 190 may include or take the form of one or more computer-readablestorage media that may be read or accessed by processor(s) 188. The oneor more computer-readable storage media can include volatile and/ornon-volatile storage components, such as optical, magnetic, organic, orother memory or disc storage, which may be integrated in whole or inpart with at least one of processor(s) 188. In some embodiments, memory190 may be implemented using a single physical device (e.g., oneoptical, magnetic, organic, or other memory or disc storage unit), whilein other embodiments, memory 190 may be implemented using two or morephysical devices.

In some embodiments, the operations executable by controller 186 mayinclude determining control signal 192 to compensate for a focus shiftbetween lens(es) 112 and image sensor 140. In such scenarios, theoperations may also include providing control signal 192 to actuator(s)194. Control signal 192 may be configured to cause actuator(s) 194 tomove image sensor 140 to the target position relative to lens assembly110.

In embodiments involving thermal sensor 170, the operations couldadditionally or alternatively include receiving, from thermal sensor170, information indicative of a current temperature of at least aportion of sensor system 100. In such scenarios, determining controlsignal 192 could be based, at least in part, on the current temperature.For example, the target position of image sensor 140 may be determinedbased on the current temperature.

In embodiments involving capacitive position sensor 180, the operationsmay additionally or alternatively include receiving, from capacitiveposition sensor 180, information indicative of a relative position ofimage sensor 140 with respect to lens assembly 110 and/or lens holder120. In such scenarios, determining control signal 192 could be based onthe relative position of image sensor 140 with respect to lens assembly110.

In some embodiments, the operations could additionally or alternativelyinvolve obtaining, from image sensor 140, image data representing anobject in an environment, and determining, based on the image data, afocus score indicative of an extent of focus and/or defocus associatedwith the object. That is, an extent to which image sensor 140 is outsideof focal plane 118 and/or outside of the depth of focus may bequantified using image data generated by image sensor 140. Accordingly,the target position for image sensor 140 may be determined based on thefocus score, thereby compensating for the observed defocus associatedwith the object in the environment.

For example, the focus score may be generated by a contrast detectionauto-focus algorithm, a phase detection auto-focus algorithm, and/or amachine learning model (e.g., an artificial neural network) that hasbeen trained to quantify the extent of focus and/or defocus, among otherpossibilities. In some cases, the object represented by the image datamay be a calibration target, such as a Modulation Transfer Function(MTF) target with known and/or expected properties. Additionally oralternatively, the image data may be captured under known and/orpredetermined conditions, including a known and/or predetermineddistance between sensor system 100 and the object, and/or known and/orpredetermined lighting conditions, among others.

FIG. 2 illustrates optical system 200. Optical system 200 may includeelements that are similar or identical to those of sensor system 100(e.g., optical system 200 may include fewer or more elements than sensorsystem 100), as illustrated and described in relation to FIG. 1 . Forexample, optical system 200 may include substrate 130 having firstsurface/side 132 (e.g., top surface/side) and second surface/side 134(e.g., bottom surface/side). Image sensor 140 may be mounted directly orindirectly (e.g., via a readout integrated circuit (ROIC)) to firstsurface/side 132 of substrate 130. In some embodiments, optical element210 (e.g., an infrared filter) could be disposed along optical axis 114.

Optical system 200 may include actuator(s) 194 disposed between lensholder 120 and substrate 130. Lens holder 120 may be coupled to part oflens assembly 110, which may include one or more lens(es) 112, which maydefine optical axis 114, focal distance 116, and/or focal plane 118.Actuator(s) 194 may be configured to control a relative position ofimage sensor 140 with respect to lens assembly 110. In someimplementations, actuator(s) 194 may at least partially surround imagesensor 140 and/or optical element 210, among other components. Forexample, the piezoelectric tube may continuously surround image sensor140 (i.e., image sensor 140 may be disposed in an interior volume of thepiezoelectric tube). In another example, stacks of the piezoelectriclinear actuators may be disposed around image sensor 140 in adiscontinuous fashion, such that space between these stacks may remainvacant.

Optical system 200 may include capacitive position sensor 180 andthermal sensor 170. It will be understood that while FIG. 2 illustratescapacitive position sensor 180 and thermal sensor 170 at particularlocations with respect to other elements of optical system 200, otherlocations of capacitive position sensor 180 and thermal sensor 170 arepossible and contemplated. Arrow 202 provides a reference point betweenthe view of FIG. 2 and the views of FIGS. 4A, 4B, and 4C.

III. EXAMPLE VEHICLES

FIGS. 3A, 3B, 3C, 3D, and 3E (i.e., FIGS. 3A-3E) show an example vehicle300 that can include some or all aspects of sensor systems and/or theoptical systems described herein. In some embodiments, vehicle 300 couldbe a semi-autonomous vehicle configured to provide some drivingautomation to a human operator (e.g., driver assistance, adaptive cruisecontrol, etc.) and/or a fully-autonomous vehicle configured to operatewith little to no human interaction. Although vehicle 300 is illustratedin FIGS. 3A-3E as a van for illustrative purposes, the presentdisclosure is not so limited. For example, vehicle 300 can represent atruck, a car, a semi-trailer truck, a motorcycle, a golf cart, anoff-road vehicle, a farm vehicle, or a drone that can navigate withinits environment using sensors and other information about itsenvironment.

Vehicle 300 may include a sensor unit 302, first lidar unit 304, secondlidar unit 306, first radar unit 308, second radar unit 310, firstlidar/radar unit 312, second lidar/radar unit 314, and two additionallocations 316 and 318 at which a radar unit, a lidar unit, a laserrangefinder unit, an audio sensor, an inertial sensor, a camera device,and/or other type of sensor(s) could be located on vehicle 300. Each offirst lidar/radar unit 312 and second lidar/radar unit 314 can take theform of a lidar unit, a radar unit, or both. First and second radarunits 308 and 310, and/or first and second lidar units 304 and 306 canactively scan the surrounding environment for the presence of potentialobstacles.

Sensor unit 302 may be mounted atop vehicle 300 and may include one ormore sensors configured to detect information about an environmentsurrounding vehicle 300, and output indications of the information. Forexample, sensor unit 302 may include any combination of cameras, radars,lidars, range finders, inertial sensors, humidity sensors, and acousticsensors. Sensor unit 302 may include one or more movable mounts that maybe operable to adjust the orientation of one or more sensors in sensorunit 302. In one embodiment, the movable mount may include a rotatingplatform that may scan sensors so as to obtain information from eachdirection around vehicle 300. In another embodiment, the movable mountof sensor unit 302 could be movable in a scanning fashion within aparticular range of angles (e.g., azimuths and/or elevations). Sensorunit 302 could be mounted atop the roof of a car, although othermounting locations are possible.

Additionally, the sensors of sensor unit 302 could be distributed indifferent locations and need not be collocated in a single location.Some possible sensor types and mounting locations include the twoadditional locations 316 and 318. Furthermore, each sensor of sensorunit 302 can be configured to be moved or scanned independently of othersensors of sensor unit 302.

In an example configuration, one or more radar scanners (e.g., first andsecond radar units 308 and 310) may be located near the rear of vehicle300, to actively scan the environment near the back of vehicle 300 forthe presence of radio-reflective objects. Similarly, first lidar/radarunit 312 and second lidar/radar unit 314 may be mounted near the frontof vehicle 300 to actively scan the environment near the front ofvehicle 300. A radar scanner can be situated, for example, in a locationsuitable to illuminate a region including a forward-moving path ofvehicle 300 without occlusion by other features of vehicle 300. Forexample, a radar scanner can be embedded in and/or mounted in or nearthe front bumper, front headlights, cowl, and/or hood, etc. Furthermore,one or more additional radar scanning devices can be located to activelyscan the side and/or rear of vehicle 300 for the presence ofradio-reflective objects, such as by including such devices in or nearthe rear bumper, side panels, rocker panels, and/or undercarriage, etc.

Although not shown in FIGS. 3A-3E, vehicle 300 can include a wirelesscommunication system. The wireless communication system may includewireless transmitters and receivers that could be configured tocommunicate with devices external or internal to vehicle 300.Specifically, the wireless communication system could includetransceivers configured to communicate with other vehicles and/orcomputing devices, for instance, in a vehicular communication system ora roadway station. Examples of such vehicular communication systemsinclude DSRC, radio frequency identification (RFID), and other proposedcommunication standards directed towards intelligent transport systems.

Vehicle 300 may include a camera, possibly at a location inside sensorunit 302. The camera can be a photosensitive instrument, such as a stillcamera, a video camera, etc., that is configured to capture a pluralityof images of the environment of vehicle 300. To this end, the camera canbe configured to detect visible light, and can additionally oralternatively be configured to detect light from other portions of thespectrum, such as infrared or ultraviolet light. The camera can be atwo-dimensional detector, and can optionally have a three-dimensionalspatial range of sensitivity.

In some embodiments, the camera can include, for example, a rangedetector configured to generate a two-dimensional image indicatingdistance from the camera to a number of points in the environment. Tothis end, the camera may use one or more range detecting techniques. Forexample, the camera can provide range information by using a structuredlight technique in which vehicle 300 illuminates an object in theenvironment with a predetermined light pattern, such as a grid orcheckerboard pattern and uses the camera to detect a reflection of thepredetermined light pattern from environmental surroundings. Based ondistortions in the reflected light pattern, vehicle 300 can determinethe distance to the points on the object. The predetermined lightpattern may comprise infrared light, or radiation at other suitablewavelengths for such measurements.

In some examples, the camera can be mounted inside a front windshield ofvehicle 300. Specifically, the camera can be situated to capture imagesfrom a forward-looking view with respect to the orientation of vehicle300. Other mounting locations and viewing angles of camera can also beused, either inside or outside vehicle 300. Further, the camera can haveassociated optics operable to provide an adjustable field of view. Stillfurther, the camera can be mounted to vehicle 300 with a movable mountto vary a pointing angle of the camera, such as via a pan/tiltmechanism.

A control system of vehicle 300 may be configured to control vehicle 300in accordance with a control strategy from among multiple possiblecontrol strategies. The control system may be configured to receiveinformation from sensors coupled to vehicle 300 (on or off vehicle 300),modify the control strategy (and an associated driving behavior) basedon the information, and control vehicle 300 in accordance with themodified control strategy. The control system further may be configuredto monitor the information received from the sensors, and continuouslyevaluate driving conditions; and also may be configured to modify thecontrol strategy and driving behavior based on changes in the drivingconditions.

In some embodiments, sensor units 302, 304, 306, 308, 310, 312, and/or314 may include systems 100, 200, 400, 430, and/or 460 as illustratedand described in relation to FIGS. 1, 2, 4A, 4B, and 4C, respectively.For example, systems 100, 200, 400, 430, and/or 460 could be implementedwith the LIDAR sensors and/or camera sensors of vehicle 300 tocompensate for thermal expansion effects that may otherwise negativelyaffect optical system performance. The actuator(s) 194 of such opticalsystems could be configured to adjust an axial position of therespective image sensors 140 with respect to the respective lensassemblies 110 and/or respective lens(es) 112. It will be understoodthat the optical systems described herein could be incorporated in otherways with respect to vehicle 300. In other words, the optical systemsdescribed elsewhere herein may be coupled to vehicle 300 and/or may beutilized in conjunction with various operations of vehicle 300. As anexample, systems 100, 200, 400, 430, and/or 460 could be utilized inself-driving or other types of navigation, planning, perception, and/ormapping operations of vehicle 300. In general, systems 100, 200, 400,430, and/or 460 could be utilized by vehicle 300 in any operating modethat uses data generated by one or more of these systems.

IV. EXAMPLE CAPACITIVE POSITION SENSING ARRANGEMENTS

FIG. 4A illustrates optical system 400. At least some elements ofoptical system 400 could be similar or identical to the elements ofsystems 100 or 200 (e.g., optical system 400 may include fewer or moreelements than systems 100 and/or 200), as illustrated and described inrelation to FIGS. 1 and 2 , and/or could be combined therewith. Asillustrated in FIG. 4A, optical system 400 may include a “stackup” ofactuator(s) 194, substrate 130, and lens assembly 110. Alternativestackups are possible and contemplated.

Specifically, lens assembly may include lens holder 120, which may befixedly connected to actuator frame 160. In one example, lens holder 120may be coupled to actuator frame 160 by way of adhesive 426 and adhesive428. In another example, lens holder and actuator frame 160 may beintegral with one another, and adhesive 426 and 428 may thus be omitted.Actuator(s) 194 may be mounted to actuator frame 160, substrate 130 maybe mounted to actuator(s) 194, and image sensor 140 may be mounted tosubstrate 130. Thus, actuator frame 160 may provide a fixed physicalreference relative to which substrate 130 may be repositioned byactuator(s) 194 to move image sensor 140 relative to lens assembly 110.

Optical system 400 may additionally include a capacitive positionsensor, which may include at least one capacitor formed by a firstcapacitive plate coupled to and/or defined on substrate 130 and a secondcapacitive plate coupled to and/or defined by a portion of lens assembly110. Specifically, the capacitive position sensor may include capacitor422 formed by (i) electrode 402 coupled to and/or defined on substrate130 and (ii) portion 412 of lens holder 120 and/or an electrode coupledto portion 412. Thus, electrode 402 may correspond to first capacitiveplate 182 of capacitive position sensor 180, and portion 412 (or theelectrode coupled thereto) may correspond to second capacitive plate184.

Specifically, portion 412 may include at least one side, face, and/orsurface that faces and is parallel with electrode 402, such that portion412 and electrode 402 form and/or approximate a parallel platecapacitor. Electrode 402 and the corresponding face of portion 412 maybe considered parallel even if these two components deviate from exactparallelism due to manufacturing variations, mechanical vibrations,and/or other factors (e.g., by up to 5 degrees). Electrode 402 may beformed using metal or other conductive material. In implementationswhere lens holder 120 is formed from a conductive material, portion 412may itself operate as the capacitive plate, since portion 412 isconductive. In implementations where lens holder 120 is formed from anon-conductive material, portion 412 may include an electrode coupled toat least the side, face, and/or surface that faces and is parallel withelectrode 402, and the electrode may operate as the capacitive plate.Other capacitors discussed herein may be structured in a manner similarto capacitor 422.

The capacitance of capacitor 422 may vary as substrate 130 movesrelative to lens assembly 110, and may thus be indicative of a relativeposition between image sensor 140 and lens assembly 110. Specifically,the capacitance of capacitor 422 may be inversely proportional to thedistance between electrodes 412 and 402, and may thus increase assubstrate 130 moves up and towards lens holder 120 and decrease assubstrate 130 moves down and away from lens holder 120.

The capacitive position sensor may also include capacitor 424 formed by(i) electrode 404 coupled to and/or defined on substrate 130 and (ii)portion 414 of lens holder 120 and/or an electrode coupled to portion414. In some implementations, electrode 402 may be physicallydiscontinuous with and/or electrically disconnected from electrode 404,and portion 412 may be physically discontinuous with and/or electricallydisconnected from portion 414. Accordingly, capacitor 422 and capacitor424 may be physically and/or electrically separate, and the respectivecapacitances thereof may be measured independently. Accordingly, aposition of the left side of substrate 130 may be determinedindependently of a position of the right side of substrate 130.

In other implementations, electrode 402 may be physically continuouswith and/or electrically connected to electrode 404, and portion 412 maybe physically continuous with and/or electrically connected to portion414. Accordingly, capacitor 422 and capacitor 424 may collectively forma single capacitor, with electrodes 402 and 404 collectively forming thefirst plate of the single capacitor and portions 412 and 414collectively forming the second plate of the single capacitor.

In order to measure the capacitance(s) of capacitor 422 and/or capacitor424, a voltage may be applied to at least one plate of capacitor 422and/or capacitor 424. The voltage may be applied by, for example,circuitry provided on substrate 130 or on another substrate presentwithin optical system 400. In one example, the voltage may be apredetermined constant voltage. Thus, for example, capacitor 422 and/orcapacitor 424 may be connected in series with at least one referencecapacitor that has a known and/or predetermined capacitance, and thecapacitance(s) of capacitor 422 and/or capacitor 424 may be determinedbased on voltage(s) measured across capacitor 422, capacitor 424, and/orthe reference capacitor. In another example, the voltage may be atime-varying voltage having a predetermined frequency. Thus, forexample, capacitance(s) of capacitor 422 and/or capacitor 424 may bedetermined based on measured impedance(s) of capacitor 422 and/orcapacitor 424 to the time-varying voltage. In some implementations, thecapacitance measurement may be facilitated by Capacitance-to-DigitalConverter AD7747 provided by ANALOG DEVICES, or a similar component.

In some implementations, portions 412 and/or 414 may be grounded, andthe voltage may be applied to electrodes 402 and/or 404, therebyallowing for a self capacitance measurement of capacitors 422 and/or424. In other implementations, actuator frame 160 may be grounded, apositive voltage may be applied to electrodes 402 and/or 404, and anegative voltage may be applied to portions 412 and/or 414 (or viceversa), thereby allowing for a transfer capacitance measurement ofcapacitors 422 and/or 424. In additional implementations, actuator frame160 and lens holder 120 may each be grounded, electrodes 402 and/or 404may each be divided into two separate electrodes, a positive voltage maybe applied to a first of the two separate electrodes, and a negativevoltage may be applied to a second of the two separate electrodes,thereby allowing for an alternative transfer capacitance measurement ofcapacitors 422 and/or 424. In further implementations, actuator frame160, electrode 402, and electrode 404 may each be grounded, and avoltage may be applied to portions 412 and/or 414. Accordingly, a firstadditional capacitor may be formed between portion 412 and actuatorframe 160 with adhesive 426 operating as a first dielectric, and asecond additional capacitor may be formed between portion 414 andactuator frame 160 with adhesive 428 operating as a second dielectric,thereby allowing for a differential capacitance measurement of capacitor422, capacitor 424, the first additional capacitor, and the secondadditional capacitor. Respective capacitances of other capacitorsdiscussed herein may be measured in similar ways.

Applying a voltage to electrode 402 and/or electrode 404 while groundingportions of lens holder 120 and/or actuator frame 160 may facilitaterouting of electrical signals from the capacitive position sensor toelectrical components that are configured to process these signals todetermine the distance between image sensor 140 and lens assembly 110.Specifically, it may be easier and/or more convenient to apply voltagesto components located on substrate 130 where electrical connectivity isreadily available, rather than to other components where electricalconnectivity may be more difficult to establish. For example, when avoltage is applied to portions of lens holder 120 and/or actuator frame160, routing of signals therefrom to substrate 130 and/or to another PCBmay involve using additional electrical connectors, which may provide anadded point of failure of optical system 400.

Although the cross-sectional view of FIG. 4A shows two capacitors (i.e.,422 and 424), additional capacitors may be disposed around image sensor140. For example, four such capacitors may be provided in a symmetricarrangement around image sensor 140, thus allowing for monitoring of thetip (e.g., rotation along y-axis) and tilt (e.g., rotation along x-axis)of image sensor 140 in addition to monitoring the position of imagesensor 140 along the z-axis. The capacitors of other optical systemsdiscussed herein may be similarly arranged.

Optical system 400 may further include housing 416, which may beconnected to lens holder 120 and/or to actuator frame 160. Housing 416may contain therein substrate 130, image sensor 140, actuator(s) 194, atleast part of lens assembly 110, and the capacitive position sensor,among other components. Housing 416 may shield and protect thesecomponents from the outside environment. Housing 416 may define thereinan opening through which one or more electrical connectors may protrudeso as to be accessible outside housing 416, thus allowing optical system400 to communicate with other components or systems. In someimplementations, thermal interface material (TIM) 418 may be disposedbetween housing 416 and actuator frame 160. Thus, heat from image sensor140 may be dissipated to housing 416 by way of substrate 130,actuator(s) 194, and TIM 418.

FIG. 4B illustrates optical system 430. At least some elements ofoptical system 430 could be similar or identical to the elements ofsystems 100, 200, and/or 400 (e.g., optical system 430 may include feweror more elements than systems 100, 200, and/or 400), as illustrated anddescribed in relation to FIGS. 1, 2, and 4A, and/or could be combinedtherewith.

Optical system 430 includes a capacitive position sensor that has adifferential architecture. The capacitive position sensor of opticalsystem 430 may include at least two capacitors, each including arespective first capacitive plate coupled to and/or defined on substrate130 and a respective second capacitive plate coupled to and/or definedby a corresponding portion of lens assembly 110. Specifically, thecapacitive position sensor may include capacitor 442 formed by (i)electrode 402 coupled to and/or defined on a first (top) side ofsubstrate 130 and (ii) portion 432 of lens holder 120 and/or anelectrode coupled to portion 432, and capacitor 446 formed by (i)electrode 406 coupled to and/or defined on a second (bottom) side ofsubstrate 130 and (ii) portion 436 of actuator frame 160 and/or anelectrode coupled to portion 436.

The capacitance of capacitors 442 and 446 may vary as substrate 130moves relative to lens assembly 110, and may thus be indicative of arelative position between image sensor 140 and lens assembly 110.Specifically, the capacitance of capacitor 442 may increase as substrate130 moves up and towards lens holder 120 and decrease as substrate 130moves down and away from the lens holder 120, while the capacitance ofcapacitor 446 may increase as substrate 130 moves down and towardsactuator frame 160 and decrease as substrate 130 moves up and away fromactuator frame 160.

The capacitive position sensor may also include capacitor 444 formed by(i) electrode 404 coupled to and/or defined on the first (top) side ofsubstrate 130 and (ii) portion 434 of lens holder 120 and/or anelectrode coupled to portion 434, and capacitor 448 formed by (i)electrode 408 coupled to and/or defined on the second (bottom) side ofsubstrate 130 and (ii) portion 438 of actuator frame 160 and/or anelectrode coupled to portion 438.

In some implementations, electrode 402 may be physically discontinuouswith and/or electrically disconnected from electrode 404, portion 432may be physically discontinuous with and/or electrically disconnectedfrom portion 434, electrode 406 may be physically discontinuous withand/or electrically disconnected from electrode 408, and/or portion 436may be physically discontinuous with and/or electrically disconnectedfrom portion 438. Accordingly, capacitors 442, 444, 446, and/or 448 maybe physically and/or electrically separate from one another, and therespective capacitances thereof may be measured independently.

In other implementations, electrode 402 may be physically continuouswith and/or electrically connected to electrode 404, portion 432 may bephysically continuous with and/or electrically connected to portion 434,electrode 406 may be physically continuous with and/or electricallyconnected to electrode 408, and/or portion 436 may be physicallycontinuous with and/or electrically connected to portion 438.Accordingly, capacitor 446 and capacitor 448 may collectively form onecapacitor, and capacitor 442 and capacitor 444 may collectively formanother capacitor.

The position of substrate 130 (and components connected thereto) may bedetermined based on a difference between a capacitance measurement ofcapacitor 442 and a capacitance measurement of capacitor 446, and/or adifference between a capacitance measurement of capacitor 444 and acapacitance measurement of capacitor 448. For example, a z-axis positionof a left side of substrate 130 may be determined by subtracting ameasured capacitance of capacitor 442 from a measured capacitance ofcapacitor 446 (i.e., D_(LEFT)=C₄₄₂−C₄₄₆), and mapping the differenceD_(LEFT) therebetween to a corresponding physical distance. Similarly, az-axis position of a right side of substrate 130 may be determined bysubtracting a measured capacitance of capacitor 444 from a measuredcapacitance of capacitor 448 (i.e., D_(RIGHT)=C₄₄₄−C₄₄₈), and mappingthe difference D_(RIGHT) therebetween to a corresponding physicaldistance. A z-axis position substrate 130 as a whole may be determinedby averaging the position of the left side thereof with the position ofthe right sides thereof, or directly based on the measured capacitances(i.e., D_(OVERALL)=(C₄₄₂+C₄₄₄)−(C₄₄₆+C₄₄₈).

The differential capacitive position sensing architecture of FIG. 4B mayprovide several improvements over the architecture of FIG. 4A. Forexample, the differential capacitive position sensing architecture ofFIG. 4B may (i) reduce and/or minimize a sensitivity of the capacitiveposition sensor to sources of common mode noise (e.g., noise experiencedequally by capacitors 442 and 446) including temperature, humidity, andcomponent aging, (ii) reduce parasitic loading on electronic componentsassociated with the capacitive position sensor, (iii) improve linearityand reduce gain error of the capacitive position sensor, and (iv)increase the sensitivity and/or resolution of the capacitive positionsensor.

The capacitive position sensors described herein may be configured tomeasure the position of substrate 130 along optical axis 114, and it maybe desirable to reduce or minimize a sensitivity of the capacitiveposition sensor to displacements in directions perpendicular to opticalaxis 114. Accordingly, an area of the capacitive plate coupled to and/orformed by lens assembly 110 (e.g., portions of lens holder 120 and/oractuator frame 160) may exceed an area of a corresponding capacitiveplate formed by the electrode coupled to substrate 130. For example, anarea of the capacitive plate formed by portion 412 may exceed an area ofelectrode 402, an area of the capacitive plate formed by portion 414 mayexceed an area of electrode 404, an area of the capacitive plate formedby portion 432 may exceed an area of electrode 402, an area of thecapacitive plate formed by portion 434 may exceed an area of electrode404, an area of the capacitive plate formed by portion 436 may exceed anarea of electrode 406, and/or an area of the capacitive plate formed byportion 438 may exceed an area of electrode 408.

In example embodiments, a width (e.g., along the x-axis) of thecapacitive plate coupled to and/or formed by lens assembly 110 mayexceed a width of the corresponding capacitive plate formed by theelectrode coupled to substrate 130, thus allowing the resultingcapacitor to exhibit no more than a threshold extent of sensitivity todisplacements along the x-axis. Additionally and/or alternatively, alength (e.g., along the y-axis) of the capacitive plate coupled toand/or formed by lens assembly 110 may exceed a length of thecorresponding capacitive plate formed by the electrode coupled tosubstrate 130, thus allowing the resulting capacitor to exhibit no morethan a threshold extent of sensitivity to displacements along they-axis.

FIG. 4C illustrates optical system 460. At least some elements ofoptical system 460 could be similar or identical to the elements ofsystems 100, 200, 400, and/or 430 (e.g., optical system 460 may includefewer or more elements than systems 100, 200, 400, and/or 430), asillustrated and described in relation to FIGS. 1, 2, 4A, and 4B, and/orcould be combined therewith.

Specifically, optical system 460 includes a capacitive position sensorthat has a tongue-and-groove arrangement. The capacitive position sensorof optical system 430 may include at least one capacitor formed by afirst groove-shaped capacitive plate coupled to and/or defined onsubstrate 130 and a second tongue-shaped capacitive plate coupled toand/or defined by a portion of lens assembly 110. Specifically, thecapacitive position sensor may include capacitor 482 formed by (i)groove electrode 472 coupled to and/or defined on the first (top) sideof substrate 130 and (ii) tongue portion 462 of lens holder 120 and/oran electrode coupled to tongue portion 462. The capacitance of capacitor482 may vary as substrate 130 moves relative to lens assembly 110, andmay thus be indicative of a relative position between image sensor 140and lens assembly 110.

The capacitive position sensor may also include capacitor 484 formed by(i) groove electrode 474 coupled to and/or defined on the first (top)side of substrate 130 and (ii) tongue portion 464 of lens holder 120and/or an electrode coupled to tongue portion 464. In someimplementations, groove electrode 472 may be physically discontinuouswith and/or electrically disconnected from groove electrode 474, andtongue portion 462 may be physically discontinuous with and/orelectrically disconnected from tongue portion 464. Accordingly,capacitor 482 and capacitor 484 may be physically and/or electricallyseparate, and the respective capacitances thereof may be measuredindependently. In other implementations, groove electrode 472 may bephysically continuous with and/or electrically connected to grooveelectrode 474, and tongue portion 462 may be physically continuous withand/or electrically connected to tongue portion 464. Accordingly,capacitor 482 and capacitor 484 may collectively form a singlecapacitor.

In some implementations, the tongue-and-groove arrangement of FIG. 4Cmay be arranged to form a differential capacitor architecture, such asthat shown in FIG. 4B. Specifically, at least one additional capacitormay be formed by a groove electrode coupled to the second (bottom) sideof substrate 130 (e.g., underneath capacitor 482) and a tongue portionof actuator frame 160.

V. EXAMPLE CAPACITIVE PLATE STRUCTURE

FIGS. 5A and 5B illustrate an example structure of the capacitive platesthat may be used in connection with optical systems 400, 430, and/or460. Specifically, a capacitive plate may include a sensor electrode anda shield electrode. For example, a capacitive plate formed on substrate130 may include sensor electrode 504, shield electrode 502, and shieldelectrode 506. Shield electrode 502 may run along a first (left) side ofsensor electrode 504, and shield electrode 506 may run along a second(right) side of sensor electrode 504. Accordingly, an electric field ofsensor electrode 504 may be “sandwiched” and/or interposed between therespective electric fields of shield electrodes 502 and 504. In someimplementations, shielding electrodes 502 and 506 may be located in adifferent vertical layer of substrate 130 than sensor electrode 504, butmay nevertheless be horizontally positioned along the first (left) sideof electrode 504 and the second (right) side of sensor electrode 504,respectively. One or more of electrodes 402, 404, 406, 408, 472, and/or474 may be structured in the manner shown in FIGS. 5A and 5B.

FIG. 5A illustrates shield electrodes 502 and 506 used in a passivemanner, while FIG. 5B illustrates shield electrodes 502 and 506 used inan active manner. Specifically, as shown in FIG. 5A, shield electrodes502 and 506 may be grounded, and may thus provide passive shielding tosensor electrode 504. Alternatively, as shown in FIG. 5B, a commonsignal may be applied to shield electrodes 502 and 506 and to sensorelectrode 504, and shield electrodes 502 and 506 may thus provide activeshielding to sensor electrode 504. Specifically, active shielding ofsensor electrode 504 may direct and/or focus the sensing zone of sensorelectrode 504, as indicated by the electric field lines emanatingperpendicularly outward from sensor electrode 504 in FIG. 5B.Additionally, active shielding may reduce an extent of environmentalinterference detected by sensor electrode 504, and reduce and/oreliminate parasitic capacitances. Passive shielding may provide some ofthe benefits of active shielding, although the magnitude of thesebenefits may be lower than for active shielding.

FIG. 6 illustrates an example arrangement of electrodes along the first(top) side of substrate 130 that may be used in connection with opticalsystems 400, 430, and/or 460. Specifically, substrate 130 may includecoupled thereto and/or defined thereon electrodes 600, 602, 604, and606. Electrodes 602 and 604 may represent electrodes 402 and 404,respectively, shown in FIGS. 4A and 4B, or groove electrodes 472 and474, respectively, shown in FIG. 4C. Each of electrodes 600, 602, 604,and 606 may be structured as shown in FIGS. 5A and 5B.

Each of electrodes 600, 602, 604, and 606 may span a correspondingportion of a periphery of substrate 130. Specifically, electrode 600 mayextend between electrodes 602 and 604 along the x-axis, and may bepositioned within a threshold distance of a top portion (as shown inFIG. 6 ) of the periphery of substrate 130. Electrode 606 may extendbetween electrodes 602 and 604 along the x-axis, and may be positionedwithin a threshold distance of a bottom portion (as shown in FIG. 6 ) ofthe periphery of substrate 130. Electrode 602 may extend betweenelectrodes 600 and 606 along the y-axis, and may be positioned within athreshold distance of a left portion (as shown in FIG. 6 ) of theperiphery of substrate 130. Electrode 604 may extend between electrodes600 and 606 along the y-axis, and may be positioned within a thresholddistance of a right portion (as shown in FIG. 6 ) of the periphery ofsubstrate 130.

In some implementations, electrodes 600, 602, 604, and 606 may beelectrically connected to one another, and may thus collectively defineone capacitive plate. In other implementations, electrodes 600, 602,604, and 606 may be electrically disconnected from one another, and eachelectrode may thus define a corresponding capacitive plate that may beused independently of other capacitive plates. Additionally, portions oflens assembly 110 that provide the second capacitive plate for each ofelectrodes 600, 602, 604, and 606 may, when viewed from the point ofview of FIG. 6 , have a cross-sectional shape that matches a shape ofthe corresponding electrode. For example, a length and width of thecapacitive plate defined by portion 412 may have a width (along thex-axis) and a length (along the y-axis) that are at least as large asthose of electrode 602.

In some implementations, each of electrodes 600, 602, 604, and 606 mayhave the same area. In some implementations, the shapes of electrodes600, 602, 604, and/or 606, as well as the shapes of the correspondingcapacitive plates formed by portions of lens assembly 110, may haveshapes other than shown in FIG. 6 . For example, the portions of lensassembly 110 may be irregularly shaped in order to accommodate placementof various components of the optical system within housing 416.Accordingly, electrodes 600, 602, 604, and/or 606 may be formed to matchthe irregular shape of the corresponding portions of lens assembly 110.

VI. ADDITIONAL EXAMPLE OPERATIONS

FIG. 7 illustrates a flow chart of operations related to controlling aposition of an image sensor based on a capacitive position measurement.The operations may be carried out by systems 100, 200, 400, 430, and/or460, among other possibilities. The embodiments of FIG. 7 may besimplified by the removal of any one or more of the features showntherein. Further, these embodiments may be combined with features,aspects, and/or implementations of any of the previous figures orotherwise described herein.

Block 700 may involve receiving, from a capacitive position sensor, acapacitance measurement indicative of a position of a substrate relativeto a lens assembly. The lens assembly may include at least one lens thatdefines an optical axis. An image sensor may be disposed on thesubstrate. The capacitive position sensor may include a first capacitiveplate coupled to the substrate and a second capacitive plate coupled tothe lens assembly.

Block 702 may involve determining, based on the capacitance measurementand a target position of the image sensor relative to the lens assembly,a control signal for an actuator. The actuator may be coupled to thesubstrate and configured to adjust the position of the substraterelative to the lens assembly to move the image sensor along the opticalaxis.

Block 704 may involve providing the control signal to the actuator tomove the substrate to the target position.

In some embodiments, the capacitive position sensor may include (i) afirst capacitor that includes the first capacitive plate and the secondcapacitive plate and (ii) a second capacitor that includes a thirdcapacitive plate and a fourth capacitive plate. The first capacitiveplate may be disposed on a first side of the substrate and the secondcapacitive plate may be disposed on a first portion of the lens assemblythat faces and is parallel to the first side of the substrate. The thirdcapacitive plate may be disposed on a second side of the substrate andthe fourth capacitive plate may be disposed on a second portion of thelens assembly that faces and is parallel to the second side of thesubstrate. The first side of the substrate may be opposite to the secondside of the substrate.

In some embodiments, the lens assembly may include (i) a lens holderfixedly connected to the at least one lens and (ii) an actuator framefixedly connected to the lens holder and configured to position theactuator in a fixed position relative to the lens holder. The firstportion of the lens assembly may include the lens holder. The secondportion of the lens assembly may include the actuator frame.

In some embodiments, determining the control signal for the actuator mayinclude determining a difference signal based on a first capacitancemeasurement of the first capacitor and a second capacitance measurementof the second capacitor, and determining a position of the substraterelative to the lens assembly based on the difference signal.

In some embodiments, the lens assembly may include (i) a lens holderfixedly connected to the at least one lens and (ii) an actuator framefixedly connected to the lens holder and configured to position theactuator in a fixed position relative to the lens holder. The capacitiveposition sensor may include (i) a first capacitor that includes thefirst capacitive plate and the second capacitive plate and (ii) a secondcapacitor that includes a third capacitive plate, a dielectric, and afourth capacitive plate. The first capacitive plate may be disposed on afirst side of the substrate and the second capacitive plate may bedisposed on a first portion of the lens holder that faces and isparallel to the first side of the substrate. The third capacitive platemay be defined by a second portion of the lens holder, the fourthcapacitive plate may be defined by a portion of the actuator frame, andthe dielectric may be defined by an adhesive configured to bond thesecond portion of the lens holder to the portion of the actuator frameand disposed therebetween.

In some embodiments, the first capacitive plate may include a groovedefined by a conductive material coupled to a first side of thesubstrate. The second capacitive plate may include a tongue defined by afirst portion of the lens assembly that faces and is parallel to thefirst side of the substrate. The tongue may be configured to fit in andmove relative to the groove.

In some embodiments, the first capacitive plate may include a sensorelectrode and one or more shield electrodes adjacent to the sensorelectrode.

In some embodiments, the capacitive position sensor may be configured toapply, to the sensor electrode and the one or more shield electrodes, acommon signal to define a sensing zone of the sensor electrode.

In some embodiments, a first width of the first capacitive plate mayexceed a second width of the second capacitive plate and a first lengthof the first capacitive plate may exceed a second length of the secondcapacitive plate such that the capacitance measurement (i) is configuredto change in response to motion of the substrate along the optical axisand (ii) exhibits no more than a threshold extent of sensitivity tomotion of the substrate perpendicular to the optical axis.

In some embodiments, the first capacitive plate may include a firstsensor electrode disposed on a first side of the substrate and extendingalong a first portion of a periphery of the substrate. The first portionof the periphery may include a first end of the substrate. The firstcapacitive plate may also include a second sensor electrode disposed onthe first side of the substrate and extending along a second portion ofthe periphery of the substrate. The second portion of the periphery mayinclude a second end of the substrate. The first end may be opposite tothe second end.

In some embodiments, the second capacitive plate coupled to the lensassembly may include a conductive portion of the lens assembly. Theconductive portion of the lens assembly may be electrically connected tothe substrate.

In some embodiments, the target position may be within a depth of focusof the at least one lens.

In some embodiments, image data representing an object in an environmentmay be obtained from the image sensor. A focus score indicative of anextent of focus associated with the object in the environment may bedetermined based on the image data. The target position may bedetermined based on the focus score.

In some embodiments, temperature data may be obtained from a temperaturesensor located within a housing that contains the lens assembly and thesubstrate. The target position may be determined based on thetemperature data.

VII. CONCLUSION

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its scope, as will be apparent to thoseskilled in the art. Functionally equivalent methods and apparatuseswithin the scope of the disclosure, in addition to those describedherein, will be apparent to those skilled in the art from the foregoingdescriptions. Such modifications and variations are intended to fallwithin the scope of the appended claims.

The above detailed description describes various features and operationsof the disclosed systems, devices, and methods with reference to theaccompanying figures. In the figures, similar symbols typically identifysimilar components, unless context dictates otherwise. The exampleembodiments described herein and in the figures are not meant to belimiting. Other embodiments can be utilized, and other changes can bemade, without departing from the scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations.

With respect to any or all of the message flow diagrams, scenarios, andflow charts in the figures and as discussed herein, each step, block,and/or communication can represent a processing of information and/or atransmission of information in accordance with example embodiments.Alternative embodiments are included within the scope of these exampleembodiments. In these alternative embodiments, for example, operationsdescribed as steps, blocks, transmissions, communications, requests,responses, and/or messages can be executed out of order from that shownor discussed, including substantially concurrently or in reverse order,depending on the functionality involved. Further, more or fewer blocksand/or operations can be used with any of the message flow diagrams,scenarios, and flow charts discussed herein, and these message flowdiagrams, scenarios, and flow charts can be combined with one another,in part or in whole.

A step or block that represents a processing of information maycorrespond to circuitry that can be configured to perform the specificlogical functions of a herein-described method or technique.Alternatively or additionally, a block that represents a processing ofinformation may correspond to a module, a segment, or a portion ofprogram code (including related data). The program code may include oneor more instructions executable by a processor for implementing specificlogical operations or actions in the method or technique. The programcode and/or related data may be stored on any type of computer readablemedium such as a storage device including random access memory (RAM), adisk drive, a solid state drive, or another storage medium.

The computer readable medium may also include non-transitory computerreadable media such as computer readable media that store data for shortperiods of time like register memory, processor cache, and RAM. Thecomputer readable media may also include non-transitory computerreadable media that store program code and/or data for longer periods oftime. Thus, the computer readable media may include secondary orpersistent long term storage, like read only memory (ROM), optical ormagnetic disks, solid state drives, compact-disc read only memory(CD-ROM), for example. The computer readable media may also be any othervolatile or non-volatile storage systems. A computer readable medium maybe considered a computer readable storage medium, for example, or atangible storage device.

Moreover, a step or block that represents one or more informationtransmissions may correspond to information transmissions betweensoftware and/or hardware modules in the same physical device. However,other information transmissions may be between software modules and/orhardware modules in different physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purpose ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

What is claimed is:
 1. An apparatus comprising: a lens assemblycomprising at least one lens that defines an optical axis; a substrate;an image sensor disposed on the substrate; an actuator coupled to thesubstrate and configured to adjust a position of the substrate relativeto the lens assembly to move the image sensor along the optical axis; acapacitive position sensor comprising (i) a first capacitor comprising afirst capacitive plate and a second capacitive plate and (ii) a secondcapacitor comprising a third capacitive plate and a fourth capacitiveplate, wherein: the first capacitive plate is coupled to a first side ofthe substrate and the second capacitive plate is coupled to a firstportion of the lens assembly that faces and is parallel to the firstside of the substrate, the third capacitive plate is coupled to a secondside of the substrate and the fourth capacitive plate is coupled to asecond portion of the lens assembly that faces and is parallel to thesecond side of the substrate, the first side of the substrate isopposite to the second side of the substrate, and the capacitiveposition sensor is configured to generate a capacitance measurementindicative of the position of the substrate relative to the lensassembly; and circuitry configured to control the actuator based on (i)the capacitance measurement and (ii) a target position of the imagesensor relative to the lens assembly.
 2. The apparatus of claim 1,wherein the second capacitive plate is formed at least in part by thefirst portion of the lens assembly, and wherein the fourth capacitiveplate is formed at least in part by the second portion of the lensassembly.
 3. The apparatus of claim 1, wherein the lens assemblycomprises (i) a lens holder fixedly connected to the at least one lensand (ii) an actuator frame fixedly connected to the lens holder andconfigured to position the actuator in a fixed position relative to thelens holder, wherein the first portion of the lens assembly comprisesthe lens holder, and wherein the second portion of the lens assemblycomprises the actuator frame.
 4. The apparatus of claim 1, wherein thecircuitry is configured to control the actuator by: determining adifference signal based on a first capacitance measurement of the firstcapacitor and a second capacitance measurement of the second capacitor;and determining a position of the substrate relative to the lensassembly based on the difference signal.
 5. The apparatus of claim 1,wherein the lens assembly comprises (i) a lens holder fixedly connectedto the at least one lens and (ii) an actuator frame fixedly connected tothe lens holder and configured to position the actuator in a fixedposition relative to the lens holder, wherein the capacitive positionsensor further comprises a third capacitor comprising a fifth capacitiveplate, a dielectric, and a sixth capacitive plate, wherein the secondcapacitive plate is disposed on a first portion of the lens holder thatfaces and is parallel to the first side of the substrate, wherein thefifth capacitive plate comprises a second portion of the lens holder,wherein the sixth capacitive plate comprises a portion of the actuatorframe, and wherein the dielectric comprises an adhesive configured tobond the second portion of the lens holder to the portion of theactuator frame and disposed therebetween.
 6. The apparatus of claim 1,wherein the first capacitive plate comprises a groove defined by aconductive material coupled to a first side of the substrate, whereinthe second capacitive plate comprises a tongue defined by the firstportion of the lens assembly, and wherein the tongue is configured tofit in and move relative to the groove.
 7. The apparatus of claim 1,wherein the first capacitive plate comprises a sensor electrode and oneor more shield electrodes adjacent to the sensor electrode.
 8. Theapparatus of claim 7, wherein the capacitive position sensor isconfigured to apply, to the sensor electrode and the one or more shieldelectrodes, a common signal to define a sensing zone of the sensorelectrode.
 9. The apparatus of claim 1, wherein a first width of thefirst capacitive plate exceeds a second width of the second capacitiveplate and a first length of the first capacitive plate exceeds a secondlength of the second capacitive plate such that the capacitancemeasurement (i) is configured to change in response to motion of thesubstrate along the optical axis and (ii) exhibits no more than athreshold extent of sensitivity to motion of the substrate perpendicularto the optical axis.
 10. The apparatus of claim 1, wherein the firstcapacitive plate comprises: a first sensor electrode disposed on a firstside of the substrate and extending along a first portion of a peripheryof the substrate, wherein the first portion of the periphery comprises afirst end of the substrate; and a second sensor electrode disposed onthe first side of the substrate and extending along a second portion ofthe periphery of the substrate, wherein the second portion of theperiphery comprises a second end of the substrate, wherein the first endis opposite to the second end.
 11. The apparatus of claim 1, wherein thesecond capacitive plate coupled to the first portion of the lensassembly comprises a conductive portion of the lens assembly, whereinthe conductive portion of the lens assembly is electrically connected tothe substrate.
 12. The apparatus of claim 1, wherein the target positionis within a depth of focus of the at least one lens.
 13. The apparatusof claim 1, wherein the circuitry is further configured to: obtain, fromthe image sensor, image data representing an object in an environment;determine, based on the image data, a focus score indicative of anextent of focus associated with the object in the environment; anddetermine the target position based on the focus score.
 14. Theapparatus of claim 1, further comprising: a housing containing the lensassembly and the substrate; and a temperature sensor located within thehousing, wherein the circuitry is further configured to: obtain, fromthe temperature sensor, temperature data; and determine the targetposition based on the temperature data.
 15. A method comprising:receiving, from a capacitive position sensor, a capacitance measurementindicative of a position of a substrate relative to a lens assembly,wherein the lens assembly comprises at least one lens that defines anoptical axis, wherein an image sensor is disposed on the substrate, andwherein the capacitive position sensor comprises (i) a first capacitorcomprising a first capacitive plate and a second capacitive plate and(ii) a second capacitor comprising a third capacitive plate and a fourthcapacitive plate, wherein: the first capacitive plate is coupled to afirst side of the substrate and the second capacitive plate is coupledto a first portion of the lens assembly that faces and is parallel tothe first side of the substrate, the third capacitive plate is coupledto a second side of the substrate and the fourth capacitive plate iscoupled to a second portion of the lens assembly that faces and isparallel to the second side of the substrate, and the first side of thesubstrate is opposite to the second side of the substrate; determining,based on the capacitance measurement and a target position of the imagesensor relative to the lens assembly, a control signal for an actuatorthat is coupled to the substrate and configured to adjust the positionof the substrate relative to the lens assembly to move the image sensoralong the optical axis; and providing the control signal to the actuatorto move the substrate to the target position.
 16. The method of claim15, wherein the second capacitive plate is formed at least in part bythe first portion of the lens assembly, wherein the fourth capacitiveplate is formed at least in part by the second portion of the lensassembly, and wherein the method further comprises: determining adifference signal based on a first capacitance measurement of the firstcapacitor and a second capacitance measurement of the second capacitor;and determining a position of the substrate relative to the lensassembly based on the difference signal.
 17. The method of claim 15,wherein the first capacitive plate comprises a sensor electrode and oneor more shield electrodes adjacent to the sensor electrode, and whereinthe method further comprises: applying, to the sensor electrode and theone or more shield electrodes, a common signal to define a sensing zoneof the sensor electrode.
 18. The method of claim 15, further comprising:obtaining, from the image sensor, image data representing an object inan environment; determining, based on the image data, a focus scoreindicative of an extent of focus associated with the object in theenvironment; and determining the target position based on the focusscore.
 19. The method of claim 15, further comprising: obtaining, from atemperature sensor, temperature data, wherein the temperature sensor islocated within a housing that contains the lens assembly and thesubstrate; and determining the target position based on the temperaturedata.
 20. A system comprising: a lens assembly comprising: (i) at leastone lens that defines an optical axis, (ii) a lens holder fixedlyconnected to the at least one lens, and (iii) an actuator frame fixedlyconnected to the lens holder; a substrate; an image sensor disposed onthe substrate; an actuator coupled to the substrate and configured toadjust a position of the substrate relative to the lens assembly to movethe image sensor along the optical axis, wherein the actuator ispositioned by the actuator frame in a fixed position relative to thelens holder; a capacitive position sensor comprising (i) a firstcapacitor comprising a first capacitive plate and a second capacitiveplate and (ii) a second capacitor comprising a third capacitive plate, adielectric, and a fourth capacitive plate, wherein: the first capacitiveplate is coupled to a first side of the substrate and the secondcapacitive plate is coupled to a first portion of the lens holder thatfaces and is parallel to the first side of the substrate, the thirdcapacitive plate comprises a second portion of the lens holder, thefourth capacitive plate comprises a portion of the actuator frame, thedielectric comprises an adhesive configured to bond the second portionof the lens holder to the portion of the actuator frame and disposedtherebetween, and the capacitive position sensor is configured togenerate a capacitance measurement indicative of the position of thesubstrate relative to the lens assembly; and circuitry configured tocontrol the actuator based on (i) the capacitance measurement and (ii) atarget position of the image sensor relative to the lens assembly.